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SUMMARY:The hidden distribution of ionized gas in Star-Forming Regions and
  Galaxies
DTSTART:20261016T080000Z
DTEND:20261016T093000Z
DTSTAMP:20261112T111700Z
UID:indico-event-67@indico.iparcos.ucm.es
DESCRIPTION:Speakers: José Eduardo Méndez-Delgado (Instituto de Astronom
 ía\, Universidad Nacional Autónoma de México (UNAM))\n\nIonized gas is 
 one of the fundamental components of galaxies. By studying its physical co
 nditions\, such as density\, temperature\, pressure\, and chemical composi
 tion\, we can investigate the formation and evolution of these systems and
  of the Universe as a whole. To determine these parameters\, we use diagno
 stics based on emission-line ratios. After correcting for extinction\, we 
 determine the electron density using the bright [SII]λλ6717\,6731 or [OI
 I]λλ3726\,3729 lines and\, when possible\, the temperature using [NII]λ
 λ5755\,6584 or [OIII]λλ4363\,5007. Once these parameters are determined
 \, we can derive masses\, pressures\, and chemical abundances with great p
 recision\, at least in principle.However\, weaker density tracers often yi
 eld puzzling discrepancies\, with estimated values differing by up to two 
 orders of magnitude. Traditionally\, it has been easy to dismiss these dis
 crepancies: perhaps the atomic data are incorrect\, perhaps the lines prob
 e a different ionization zone\, or perhaps they are simply too faint to be
  reliable. Besides\, if we can barely detect these lines in the first plac
 e\, what use are they? But the next generation of 30-meter telescopes will
  routinely detect these lines in star-forming regions across the Universe\
 , leaving us with no choice but to understand exactly what they are tellin
 g us.In this talk\, I will show that these discrepancies contain fundament
 al physical information. Using deep observations of the Orion Nebula obtai
 ned with the Sloan Digital Sky Survey V (SDSS-V) Local Volume Mapper (LVM)
 \, we simultaneously measure 16 density diagnostics originating from the s
 ame region of gas projected on the sky. We find that the differences betwe
 en their inferred densities are not random. Instead\, the densities follow
  a systematic ordering according to the atomic properties of each diagnost
 ic\, revealing a broad distribution of gas densities.This hierarchy is als
 o observed in other star-forming regions in the Milky Way\, nearby galaxie
 s\, and high-redshift systems. I will discuss how this broad density distr
 ibution could change our interpretation of many properties of ionized gas 
 throughout the Universe.\n \n\n\nhttps://indico.iparcos.ucm.es/event/67/
LOCATION:00.303.0 - Aula 13 (Facultad de Ciencias Físicas)
URL:https://indico.iparcos.ucm.es/event/67/
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